According to the recent trend of lighting technology, an LED has been employed as a light source, in order to reduce energy.
A high-brightness LED is differentiated from other light sources in terms of various aspects such as energy consumption, lifetime, and light quality.
However, since the LED is driven by a current, a lighting apparatus using the LED as a light source requires a large number of additional circuits for current driving.
In order to solve the above-described problem, an AC direct-type lighting apparatus has been developed.
The AC direct-type LED lighting apparatus generates a rectified voltage using a commercial AC power supply and drives an LED. Since the AC direct-type LED lighting apparatus directly uses the rectified voltage as an input voltage without using an inductor and capacitor, the AC direct-type LED lighting apparatus has a satisfactory power factor.
A general LED lighting apparatus is designed to be driven through a voltage obtained by rectifying commercial power. In general, a lamp of the LED lighting apparatus includes a large number of LEDs connected in series to each other.
Recently, the LED lighting apparatus has employed a dimmer using a triac, in order to control brightness. The dimmer is generally used to control the brightness of an incandescent lamp, and a constant value of current needs to be maintained for operation of the element.
The rectified voltage used for driving the LED lighting apparatus has a ripple which rises and falls. During a valley period of the ripple of the rectified voltage, a lamp of the LED lighting apparatus is turned off. While the lamp is turned off, no current flow is generated in the LED lighting apparatus.
Since no current flow is generated in the LED lighting apparatus in a state where the lamp is turned off, the LED lighting apparatus has difficulties in providing a holding current required for the operation of the triac.
When the LED lighting apparatus includes the dimmer implemented with a triac, the operation of the triac may not be maintained in case where the lamp is turned off due to the characteristic of the rectified voltage, which makes it difficult to perform brightness control.